On Tue, Jan 21, 2025 at 6:53 PM Ihor Solodrai <ihor.solodrai@xxxxx> wrote:
>
> Add the following functions to libbpf API:
> * btf__add_type_attr()
> * btf__add_decl_attr()
>
> These functions allow to add to BTF the type tags and decl tags with
> info->kflag set to 1. The kflag indicates that the tag directly
> encodes an __attribute__ and not a normal tag.
>
> See Documentation/bpf/btf.rst changes for details on the semantics.
>
> Suggested-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> Signed-off-by: Ihor Solodrai <ihor.solodrai@xxxxx>
> ---
> Documentation/bpf/btf.rst | 27 +++++++++--
> tools/include/uapi/linux/btf.h | 3 +-
kernel documentation and uapi changes should be in a separate patch
from libbpf-side changes
> tools/lib/bpf/btf.c | 87 +++++++++++++++++++++++++---------
> tools/lib/bpf/btf.h | 3 ++
> tools/lib/bpf/libbpf.map | 2 +
> 5 files changed, 93 insertions(+), 29 deletions(-)
>
Please double-check whitespacing, tabs vs space might have been messed
up in this patch.
pw-bot: cr
> diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
> index 2478cef758f8..615ded7b2442 100644
> --- a/Documentation/bpf/btf.rst
> +++ b/Documentation/bpf/btf.rst
> @@ -102,8 +102,9 @@ Each type contains the following common data::
> * bits 24-28: kind (e.g. int, ptr, array...etc)
> * bits 29-30: unused
> * bit 31: kind_flag, currently used by
> - * struct, union, fwd, enum and enum64.
> - */
> + * struct, union, enum, fwd, enum64,
> + * DECL_TAG and TYPE_TAG
keep it lower case
> + */
> __u32 info;
> /* "size" is used by INT, ENUM, STRUCT, UNION and ENUM64.
> * "size" tells the size of the type it is describing.
[...]
> -/*
> - * Append new BTF_KIND_DECL_TAG type with:
> - * - *value* - non-empty/non-NULL string;
> - * - *ref_type_id* - referenced type ID, it might not exist yet;
> - * - *component_idx* - -1 for tagging reference type, otherwise struct/union
> - * member or function argument index;
> - * Returns:
> - * - >0, type ID of newly added BTF type;
> - * - <0, on error.
> - */
> -int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
> - int component_idx)
> +
> +static int __btf__add_decl_tag(struct btf *btf, const char *value,
> + int ref_type_id, int component_idx, int kflag)
nit: please call it "btf_add_decl_tag" (to distinguish it from public
API, but also not use double-underscored name unnecessarily)
> {
> struct btf_type *t;
> int sz, value_off;
[..]
